Biology(Part 8)

Artificial and Natural Classification in Taxonomy

The differences between "artificial" and "natural" classifications are differences in degree, and not in kind. In each case the classification depends upon likeness; but in an artificial classification some prominent and easily observed feature is taken as the mark of resemblance or dissemblance; while, in a natural classification, the things classified are arranged according to the totality of their morphological resemblances, and the features which have been ascertained by observation to be the indications of many likenesses or unlikenesses. And thus a natural classification is a great deal more than a mere index. It is a statement of the marks of similarity of organization; of the kinds of structure which, as a matter of experience, are found universally associated together; and, as such, it furnishes the whole foundation for those indications by which conclusions as to the nature of the whole of an animal are drawn from a knowledge of some part of it.

When a paleontologist argues from the characters of a bone or of a shell to the nature of the animal to which that bone or shell belonged, he is guided by the empirical morphological laws established by wide observation, that such a kind of bone or shell, is associated with such and such features in the rest of the body, and no others. And it is these empirical laws which are embodied and expressed in a natural classification.